US4233005A - Hydraulic gear pump with recesses in non-working gear flanks - Google Patents

Hydraulic gear pump with recesses in non-working gear flanks Download PDF

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Publication number
US4233005A
US4233005A US05/974,039 US97403978A US4233005A US 4233005 A US4233005 A US 4233005A US 97403978 A US97403978 A US 97403978A US 4233005 A US4233005 A US 4233005A
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United States
Prior art keywords
gears
tooth
inter
volume
inlet port
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/974,039
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English (en)
Inventor
Harry S. Bottoms
Ronald A. Heath
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ZF International UK Ltd
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Lucas Industries Ltd
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Filing date
Publication date
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/082—Details specially related to intermeshing engagement type machines or pumps
    • F04C2/088—Elements in the toothed wheels or the carter for relieving the pressure of fluid imprisoned in the zones of engagement

Definitions

  • This invention relates to hydraulic pumps of the kind having a pair of intermeshed, externally toothed gear elements, and in particular to such pumps when intended for use in aircraft fuel systems.
  • each inter-tooth volume first reduces and subsequently increases.
  • the proportions of the inter-tooth volume on respective sides of the backlash gap also alter, so that fluid is transferred from one side of the backlash gap to the other side thereof, within the inter-tooth volume.
  • These volume changes result in transient pressure changes within the inter-tooth volumes.
  • reductions in fuel pressures as a result of the aforesaid volume changes will result in air coming out of solution, and in the creation of bubbles of fuel vapour.
  • a subsequent increase in fuel pressure will result in collapse of the vapour bubbles.
  • the low air content of the fuel will result in rapid collapse of the vapour bubbles which, if occurring close to a metal surface, will cause cavitation erosion.
  • the present invention in effect, causes the inter-tooth volumes to communicate with the pump inlet port before these volumes increase from their minimum value.
  • a hydraulic pump comprising a housing, a pair of meshed externally-toothed gear elements in a chamber within the housing, said housing having inlet and outlet ports which communicate with said chamber on opposite sides of a zone in which said gear elements are meshed, the non-working flank of each gear tooth having recesses adjacent the end faces of the gear element and an unrecessed land extending from the root to the tip of the tooth between said recesses, adjacent pairs of contact points between said gears defining, together with said non-working flanks, an inter-tooth volume whose capacity changes as said gears rotate, each said inter-tooth volume comprising two volumes on respective sides of a minimum clearance between said non-working flanks, one of said two volumes increasing and the other of said two volumes decreasing after said minimum clearance has passed through the pitch point of the gears, said inlet port, said inter-tooth volumes being dimensioned so that each said inter-tooth volume first communicates with said inlet port at a time not later than that at which said minimum clearance passes through said pitch point
  • FIG. 1 is a longitudinal section through a gear pump
  • FIG. 2 is a section on line 2--2 in FIG. 1,
  • FIG. 3 is a section on lines 3--3 in FIG. 1,
  • FIG. 4 is an enlarged perspective view of one tooth of a gear forming part of the pump
  • FIG. 5 is an end view of part of a gear element of the pump
  • FIG. 6 is a diagram illustrating the parameters referred to in the description
  • FIG. 7 is an enlarged view, corresponding to a part of FIG. 3 of one relative position of the meshed gear elements
  • FIGS. 8 and 9 are views, corresponding to FIG. 7 of other relative mesh positions of the gear elements.
  • the pump includes a housing 10 formed with a pair of identical parallel bores whose axes are spaced by a distance less than the diameter of the bores so as to define a chamber 11 within the housing 10.
  • Mounted within these bores are two pairs of bearing blocks 12, 13, 14, 15 each of which has a part cylindrical surface and a flat surface which abuts a flat surface in the other block of the pair.
  • the blocks 12, 13, 14, 15 support trunnions 16 on two gears 17, 18 of identical pitch diameters which are interposed between the bearing blocks and are meshed together.
  • the gear 17 is connected to a splined drive shaft 19, and the gear 18 is driven by the gear 17.
  • the housing 10 has an inlet port 20 and an outlet port 21 which communicate with the chamber 11 on opposite sides of the zone of mesh of the gears 17, 18.
  • the bearing blocks 12, 13, 14, 15 sealingly abut the end faces of the gear elements 17, 18.
  • Each tooth 22 of each gear 17, 18 as shown in FIGS. 4 and 5 a working flank 23 and a non-working flank 24.
  • the non-working flanks 24 of all the teeth of both gears are provided with interpenetrating recesses 25, 26 which are milled out of the non-working flanks adjacent the end faces of the gears, so as to leave an unrelieved land 27 which extends from the root to the tip of the non-working face between one of the recess groups 25, 26 and the other recess group.
  • the angular dimensions of the recesses 25, 26 and their position in relation to the tooth form is shown more clearly in FIG. 5.
  • the gears 17, 18 are involute gears having a pressure angle of 30°.
  • the base circle BC of the gear 17 and the pitch circles PC of both gears are indicated, as is the contact line CL between the gears.
  • the gear 17 is drivingly rotated clockwise, and drives the gear 18 anticlockwise.
  • the backlash gap 28 between the non-working flanks 24 of the gears lies on the pitch point PP, that is at the point at which the pitch circles PC touch and through which the contact line CL passes.
  • the base pitch BP is indicated and is the distance between a leading meshing point 29 of a tooth of the drive gear 17 and a trailing meshing point 30 on the next adjacent tooth of the driver gear 17.
  • inter-tooth volume made up of two volumes V1, V2 on either side of the backlash gap 28.
  • volumes V1 and V2 are equal, and the total capacity of the inter-tooth volume is at its minimum.
  • FIG. 6 is diagrammatic only, and for the purpose of providing a definition of the terms subsequently used.
  • the gear teeth are shown in FIG. 6 without their recesses 25, 26 but it will be understood that in practice the volumes V1 and V2 each include the additional volumes provided by two recesses 25 and two recesses 26.
  • the capacity of the inter-tooth volume is thus increased, and the change in this capacity as the gears rotate is thereby a smaller percentage of the whole. Pressure changes within the inter-tooth volume are thereby reduced.
  • the recesses 25, 26 allow fuel to flow between the volumes V1 and V2 without being required to pass through the restriction formed by the backlash gap 28. Flow between the volumes V1 and V2 is thus at a relatively low velocity and does not cause turbulence which can give rise to cavitation.
  • each bearing block has two relieved zones 31, 32 or 33, 34 which communicate with the respective ports 20, 21.
  • the relieved zones are separated by bridge portions 35, 36 which prevent direct flow through the relieved zones from the outlet port 21 back to the inlet port 20.
  • FIGS. 7, 8 and 9 show the relationship between the relieved portions on the bearing blocks and the recesses in the gear teeth, which permit the inter-tooth volumes to communicate with the inlet and outlet ports.
  • the bearing blocks are shown in dotted outline, so that the relative positions of the relieved portions, 31, 32, 33, 34 and bridge portions 35, 36 relative to the backlash space may be more readily distinguished.
  • FIG. 7 shows the relative positions of the gears just as the volume V2, which includes the recess 25 on one tooth and the recess 26 on an adjacent tooth, is about to communicate with the inlet port 20 by way of the recess 34.
  • the leading contact point 29 between the driver and driven gears is spaced by a distance X from the pitch point PP.
  • the distance X is between 0.4 BP and 0.5 BP.
  • the value of X is 0.45 BP.
  • the inter-tooth volume communicates with the inlet port 20, by way of the relieved portion 34, before the size of the inter-tooth volume has started to increase. There is thus at this stage no tendency for fuel to be drawn from the inlet port 20 into the inter-tooth volume.
  • both the volumes V1 and V2 are in communication with the high pressure in the outlet port 21, via the relieved portions 31, 33. In the position shown in FIG. 7, therefore, fuel will tend to be expelled from the inter-tooth volume towards the inlet port 20, and bubbles likely to result in cavitation are expelled away from the gear teeth.
  • FIG. 8 shows the relative positions of the gears and of the bridge portions 35, 36 when the leading meshing point 29 has moved to an increased distance X from the pitch point PP.
  • the condition shown in FIG. 8 corresponds generally to that shown in FIG. 6, the value X being between 0.45 BP and 0.55 BP, subject to the proviso that the value of X shown in FIG. 8 is greater than that shown in FIG. 7.
  • the value of X shown in FIG. 8 is 0.5 BP.
  • the backlash gap 28 lies on the pitch point PP and the inter-tooth volume has just ceased communication with the relieved portions 31, 33 and hence is shut off from the outlet port 21.
  • the inter-tooth volume is in communication with the inlet port, by way of the relieved portion 34, but since this volume is at its minimum value there is no tendency for fuel to flow into the inter-tooth volume at this time.
  • the leading contact point 29 has moved still further to a distance X of between 0.5 BP and 0.6 BP from the pitch point.
  • the distance X is 0.55 BP.
  • the inter-tooth volume first communicates with the relieved portion 32.
  • the volume V2 is decreasing and the volume V1 is increasing at a greater rate.
  • cavitation bubbles initially expelled in the conditions shown in FIGS. 7 and 8, to re-enter the volume V2. It has been found that substantially all cavitation bubbles are expelled from the inter-tooth volume during the stages shown in FIGS. 7 and 8 and these bubbles are thereby kept away from the tooth flanks until after the bubbles collapse.
  • volume V2 The drop in pressure in volume V2 as the latter communicates with the recess 34 is very rapid, since there is a considerable pressure difference, prior to this communication, between the fuel in the inter-tooth volume and that in the inlet port. This rapid pressure drop might in some circumstances cause the pressure in the inter-tooth volume to "overshoot” and fall below that in the inlet port. This is, however, prevented by the fact that the volume V2 continues to decrease, and when volume V1 communicates with the recess 32, as shown in FIG. 9, flow from volume V1 to volume V2 is very small or non-existent.
  • connection of the inter-tooth volume to the inlet port before this volume reaches its minimum value that is, at the time when the pressure in the inter-tooth volume is increasing at its maximum rate, prevents this pressure from reaching an unacceptably high level.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)
US05/974,039 1978-01-18 1978-12-28 Hydraulic gear pump with recesses in non-working gear flanks Expired - Lifetime US4233005A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB199778 1978-01-18
GB1997/78 1978-01-18

Publications (1)

Publication Number Publication Date
US4233005A true US4233005A (en) 1980-11-11

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US05/974,039 Expired - Lifetime US4233005A (en) 1978-01-18 1978-12-28 Hydraulic gear pump with recesses in non-working gear flanks

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US (1) US4233005A (US20030204162A1-20031030-M00001.png)
JP (1) JPS6024316B2 (US20030204162A1-20031030-M00001.png)
DE (1) DE2901179C2 (US20030204162A1-20031030-M00001.png)
FR (1) FR2415215A1 (US20030204162A1-20031030-M00001.png)
IT (1) IT1111757B (US20030204162A1-20031030-M00001.png)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4934913A (en) * 1988-02-19 1990-06-19 Otto Eckerle Gmbh & Co. Kg Internal-gear machine with fluid opening in non-bearing tooth flank
US6283735B1 (en) 1998-10-13 2001-09-04 SCHWäBISCHE HüTTENWERKE GMBH Variable-delivery external gear pump
US6623262B1 (en) 2001-02-09 2003-09-23 Imd Industries, Inc. Method of reducing system pressure pulsation for positive displacement pumps
US20050271538A1 (en) * 2004-06-04 2005-12-08 Entek Manufacturing, Inc. Gear for use in a gear pump
US20060067849A1 (en) * 2004-09-28 2006-03-30 Aisin Seiki Kabushiki Kaisha Rotor structure of inscribed gear pump
US20070092392A1 (en) * 2005-10-20 2007-04-26 Aisin Seiki Kabushiki Kaisha Internal gear pump
US20070178003A1 (en) * 2005-11-22 2007-08-02 Parker-Hannifin Corporation Gear pump with ripple chamber for low noise and pressure ripples
US20070292295A1 (en) * 2006-06-15 2007-12-20 White Drive Products, Inc. Rotor with cut-outs
EP3193019A1 (en) * 2016-01-12 2017-07-19 Hamilton Sundstrand Corporation A gear pump
US9874208B2 (en) 2015-01-21 2018-01-23 Hamilton Sunstrand Corporation Bearing faces with fluid channels for gear pumps
CN109604345A (zh) * 2017-08-25 2019-04-12 柯克斯特科尼克股份有限公司 用于通过偏心衬套之间的非对称齿部轧制棒形轧材的可调节的轧机机架和具有非对称齿部的偏心衬套
US10443597B2 (en) 2016-01-12 2019-10-15 Hamilton Sundstrand Corporation Gears and gear pumps
US10989190B2 (en) * 2015-12-04 2021-04-27 Audi Ag External gear pump
US11365732B1 (en) * 2014-05-21 2022-06-21 Laverne Schumann High volume pump system
US11493037B1 (en) 2014-05-21 2022-11-08 Laverne Schumann Pump system

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8137085B2 (en) * 2008-12-18 2012-03-20 Hamilton Sundstrand Corporation Gear pump with slots in teeth to reduce cavitation
DE102013226852A1 (de) * 2013-12-20 2015-06-25 Volkswagen Aktiengesellschaft Zahnradpumpe
DE102017102856A1 (de) 2017-02-13 2018-08-16 Schwäbische Hüttenwerke Automotive GmbH Zahnrad mit Druckausgleichstasche

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1686867A (en) * 1926-11-03 1928-10-09 Lewis O Kuhn Gear pump
DE722158C (de) * 1940-01-24 1942-07-09 Rossweiner Metallwarenfabrik C Zahnradpumpe
US2344628A (en) * 1940-12-26 1944-03-21 Gar Wood Ind Inc Gear pump
US2354992A (en) * 1941-11-11 1944-08-01 Westinghouse Electric & Mfg Co Gear pump
GB578809A (en) * 1944-02-21 1946-07-12 Prec Developments Co Ltd Improvements in gear pumps
US2601003A (en) * 1946-05-17 1952-06-17 Bendix Aviat Corp Gear pump
GB739357A (en) * 1954-01-28 1955-10-26 Dowty Hydraulic Units Ltd Improvements relating to gear pumps
US3113524A (en) * 1961-12-26 1963-12-10 Roper Hydraulics Inc Gear pump with trapping reliefs
US3303792A (en) * 1964-04-20 1967-02-14 Roper Ind Inc Gear pump with trapping reliefs
US3439625A (en) * 1966-03-23 1969-04-22 Lucas Industries Ltd Gear pumps
US3953160A (en) * 1973-03-15 1976-04-27 Lucas Aerospace Limited Gear pumps and motors

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE366152C (de) * 1922-12-30 Bbc Brown Boveri & Cie Einrichtung zur Vermeidung der Quetschwirkung bei Zahnrad-OElpumpen
DE2249952C3 (de) * 1972-10-12 1975-03-27 Zahnradfabrik Friedrichshafen Ag, 7990 Friedrichshafen Hydraulische Zahnradmaschine
DK135919B (da) * 1972-11-03 1977-07-11 Comp Generale Electricite Fremgangsmåde til fremstilling af akkumulator-elektroder.
US3981646A (en) * 1973-03-15 1976-09-21 Lucas Aerospace Limited Gear pumps and motors

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1686867A (en) * 1926-11-03 1928-10-09 Lewis O Kuhn Gear pump
DE722158C (de) * 1940-01-24 1942-07-09 Rossweiner Metallwarenfabrik C Zahnradpumpe
US2344628A (en) * 1940-12-26 1944-03-21 Gar Wood Ind Inc Gear pump
US2354992A (en) * 1941-11-11 1944-08-01 Westinghouse Electric & Mfg Co Gear pump
GB578809A (en) * 1944-02-21 1946-07-12 Prec Developments Co Ltd Improvements in gear pumps
US2601003A (en) * 1946-05-17 1952-06-17 Bendix Aviat Corp Gear pump
GB739357A (en) * 1954-01-28 1955-10-26 Dowty Hydraulic Units Ltd Improvements relating to gear pumps
US3113524A (en) * 1961-12-26 1963-12-10 Roper Hydraulics Inc Gear pump with trapping reliefs
US3303792A (en) * 1964-04-20 1967-02-14 Roper Ind Inc Gear pump with trapping reliefs
US3439625A (en) * 1966-03-23 1969-04-22 Lucas Industries Ltd Gear pumps
US3953160A (en) * 1973-03-15 1976-04-27 Lucas Aerospace Limited Gear pumps and motors

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4934913A (en) * 1988-02-19 1990-06-19 Otto Eckerle Gmbh & Co. Kg Internal-gear machine with fluid opening in non-bearing tooth flank
US6283735B1 (en) 1998-10-13 2001-09-04 SCHWäBISCHE HüTTENWERKE GMBH Variable-delivery external gear pump
US6623262B1 (en) 2001-02-09 2003-09-23 Imd Industries, Inc. Method of reducing system pressure pulsation for positive displacement pumps
US20050271538A1 (en) * 2004-06-04 2005-12-08 Entek Manufacturing, Inc. Gear for use in a gear pump
US20060067849A1 (en) * 2004-09-28 2006-03-30 Aisin Seiki Kabushiki Kaisha Rotor structure of inscribed gear pump
EP1640610A3 (en) * 2004-09-28 2006-08-16 Aisin Seiki Kabushiki Kaisha Rotor structure of inscribed gear pump
US20070092392A1 (en) * 2005-10-20 2007-04-26 Aisin Seiki Kabushiki Kaisha Internal gear pump
US20070178003A1 (en) * 2005-11-22 2007-08-02 Parker-Hannifin Corporation Gear pump with ripple chamber for low noise and pressure ripples
EP2032803A2 (en) * 2006-06-15 2009-03-11 White Drive Products Inc. Rotor with cut-outs
US7481633B2 (en) * 2006-06-15 2009-01-27 White Drive Products, Inc. Rotor with cut-outs
US20070292295A1 (en) * 2006-06-15 2007-12-20 White Drive Products, Inc. Rotor with cut-outs
EP2032803A4 (en) * 2006-06-15 2014-01-15 White Drive Products Inc ROTOR WITH CUTS
US11365732B1 (en) * 2014-05-21 2022-06-21 Laverne Schumann High volume pump system
US11493037B1 (en) 2014-05-21 2022-11-08 Laverne Schumann Pump system
US9874208B2 (en) 2015-01-21 2018-01-23 Hamilton Sunstrand Corporation Bearing faces with fluid channels for gear pumps
US10989190B2 (en) * 2015-12-04 2021-04-27 Audi Ag External gear pump
EP3193019A1 (en) * 2016-01-12 2017-07-19 Hamilton Sundstrand Corporation A gear pump
US10443597B2 (en) 2016-01-12 2019-10-15 Hamilton Sundstrand Corporation Gears and gear pumps
US10563653B2 (en) 2016-01-12 2020-02-18 Hamilton Sundstrand Corporation Gear pump
CN109604345A (zh) * 2017-08-25 2019-04-12 柯克斯特科尼克股份有限公司 用于通过偏心衬套之间的非对称齿部轧制棒形轧材的可调节的轧机机架和具有非对称齿部的偏心衬套

Also Published As

Publication number Publication date
IT1111757B (it) 1986-01-13
JPS54108907A (en) 1979-08-27
DE2901179C2 (de) 1985-06-13
FR2415215B1 (US20030204162A1-20031030-M00001.png) 1983-03-18
DE2901179A1 (de) 1979-07-19
FR2415215A1 (fr) 1979-08-17
JPS6024316B2 (ja) 1985-06-12
IT7919157A0 (it) 1979-01-09

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